The purpose of the project was to elucidate the mechanism of release of interleukin-1beta (IL-1beta) from human monocytes and to examine the usefulness of monoclonal antibodies to modulate this release. We valuateded the hypothesis that interleukin-1beta is released from activated human monocytes through a process of "reverse" endocytosis, in which alpha2-macroglobulin (alpha2-M) acts as a carrier protein. We developed biochemical techniques for production of both "fast" and "slow" alpha2-M and SDS-PAGE and immunoblot techniques for identification and detection of these proteins. The "fast" form was pretreated with methylamine or trypsin, and is known to bind to the alpha2-M receptor. The "slow" form is untreated. We discovered that the "fast" form of alpha2-M increased IL-1beta release from lipopolysaccharide (LPS)- stimulated human monocytes, while the "slow" form had no effect. We also found that activated monocytes make and release their own form of alpha2- M, which appeared to be in the "slow" form, and that a large percentage of the IL-1beta found in human serum is, in fact, bound to this protein. The time-course for release of alpha2-M from human monocytes did not appear to correspond to the time-course for release of IL-1beta. We were unsuccessful at attempts to detect IL-1beta associated with alpha2-M either inside activated human monocytes or in the supernatants by immunoprecipitation methodology utilizing the appropriate monoclonal antibodies. This could have been due to limits of detection of the immunoblotting methodology. We were also unsuccessful at attempts to break the covalent bonds between the IL-1beta and alpha2-M once they were bound together, a technique that may have improved detection capabilities. We also considered the hypothesis that alpha2-M acted, not as a carrier of IL-1beta from the monocytes, but rather as a protease inhibitor affecting the form of IL-1beta produced and released, 17 kDa biologically active IL- 1beta versus 33 kDa precursor IL-1beta. Preliminary data suggested that "slow" alpha2-M may have increased the amount of 33 kDa precursor IL-1beta inside the activated monocytes.